I have been developing lots of websites, and I stumble upon many high profile websites & try to conclude whether using relative units (ems in my case) with restricted value is good, or should we just copy+paste whatever the value calc shows us in ems (too lenghty).
To be precise,
18px ÷ 13px =
1.3846153em _(is okay OR)_ 1.38em
I’ve used up to 3 or 4 decimal digits with font sizes which worked pretty well (for fluid layout however I had to use 6 decimal digits with % width or else Chrome would mess up). For font sizes I think the whole point of ems is not to have to think about pixels anymore, so having a ton of digits to get a nice round pixel value based on a default of 16px wouldn’t make sense.
I agree the point you have made, but also there are many who do the calculations & include those tons into css, and let browsers decide, where to shrink those decimals.
Just like you, I personally prefer deciding the value myself instead of letting browsers to decide (which may vary browser-to-browser), but then again, was wondering why many big company developers still make it a point to go that extra mile to include tons of post decimal values!